A) 0.05s
B) 0.1s
C) 0.15s
D) 0.3s
Correct Answer: B
Solution :
The current at any instant is given by \[l={{l}_{0}}\,(1-{{e}^{-Rt/L}})\,\Rightarrow \,\frac{{{l}_{0}}}{2}\,={{l}_{0}}\,(1-{{e}^{-Rt/L}})\] \[\frac{Rt}{L}\,=\ln \,2\] \[\therefore \,\,\,t=\frac{L}{R}\,\ln 2\,=\frac{300\times {{10}^{-3}}}{2}\times 0.693\]You need to login to perform this action.
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